Odd Toilet Draining Question

About 2 months ago I started to notice a constant "dripping" noise in the wall next to the toilet which became more pronounced if not an all out draining sound should the bowl become filled past it normal level. ex: if one were to pour a bucket of water in the bowl you would hear it draining before being flushed.

I noticed that the toilet would fill itself in the tank periodically so I turned off the water at the shut off valve to the toilet and noticed that the water in the tank would completely drain out. Now I am assuming it is going down the drain because I am not seeing water anywhere and I would assume if there was that much water leaking out, one would notice it and I have looked all over the house for signs of leaks and water and found none.

It was a very old toilet so I replaced it myself. An Elijer 2 piece toilet, new flexible water line, new wax ring...etc. The replacement went smooth, flange was in perfect shape as was the floor (no water damage)

Now, the water is no longer leaking out of the tank. But, the toilet sounds as though it is "draining" or "dripping" when the bowl fluid level increases beyond the normal tank level.

The toilet sounds as tough it is "draining" or "dripping" when the bowl fluid level increases beyond the normal bowl level.

Ex: If we were to pour a bucket of water into the toilet bowl, I hear water either "flowing" or "dripping" though the pipes even before it is flushed.

Once the water level in the bowl is back to its normal level it stops.

The toilet is not running constantly or leaking out of the tank. Just happens when the water level in the bowl portion of the tank increases.

Again, I only noticed this start to happen a few months ago, find no signs of leaks, new toilet...any ideas?

The problem with the old toilet sounds like just the old rubber flapper was leaking. They may look "normal", but they all get weak and eventually start to leak from the tank into the bowl, and just need to be replaced periodically.
You didn't necessarily need to replace the toilet.
Take the tank lid off and make sure that the refill assembly is properly adjusted so that it cuts off at the horizontal water level indentation inside the tank, or about 1/2" or so below the top of the overflow pipe in the middle of the tank.
If you have a float-cup type, you can adjust the water level by twisting the assembly shaft or pinching the float-cup clip on the little rod beside it to slide it up or down to adjust the water cut-off level. If you have a float-ball type, carefully bend the ball rod down to adjust the cut-off.
Make sure that the refull tube water flows only into the overflow pipe.
Adjust the flapper chain so that it just allows the flapper to close fully.
Toilets have built-in traps, and any time that the water in the bowl rises high enough, the bowl water will "leak" out of the trap into the drain pipes.
I think that you just need to do a little adjusting inside the tank.
Good luck!
Mike

Is your toilet flapper on a rubber ring around the overflow tube?
Does the bottom of your overflow tube have little L-shaped brackets on it?
If the answer is yes to both questions, cut out the rubber ring and install the flapper on the L-shaped brackets by the little rubber "ears" on the flapper.
They seem to work better for me that way for some reason.
Anytime that water is high enough in the bowl, it will begin flowing through the built-in toilet trap. A draining noise would be normal in that case, and there may even be a little dripping noise afterwards, depending upon how things are plumbed behind it.
If nothing is leaking outside the drain pipes, and everything is working fine with the toilet, I don't know if I wouldn't just leave well enough alone for a while.
Mike